Quantification
of CMRO2 and CBF Using Simultaneous NIRS and FMRI

Sungho Tak1, Jong Chul Ye1

1Bio and Brain Engineering, KAIST, Daejeon, Korea

This paper introduces an accurate technique to estimate
the cerebral metabolic rate of oxygen (CMRO2) and cerebral blood
flow (CBF) using simultaneously measured near infrared spectroscopy (NIRS) and
blood oxygenation level dependent (BOLD) fMRI signals. Owing to simultaneous
acquisition of both fMRI and NIRS, separate hypercapnia condition or arterial
spin labeling (ASL) acquisition are not necessary to quantify CMRO2
and CBF, which greatly improves the accuracy of the proposed method. The
dynamic coupling ratio of CBF changes to CMRO2 changes has been also
investigated. Experimental results using finger tapping task showed that the
activation pattern of CBF calculated using NIRS-SPM software is more specific
to the primary motor cortex than fMRI BOLD and NIRS-HbR signal. Furthermore,
the dynamic couple ratio coincides with the existing results from the
literature.